Question: What number makes this equation true? $719 = 57 + $
Solution: $719 = 57 +{{?}}$ ${57}$ ${719}$ $+?$ Let's start by adding hundreds to ${57}$ until we get as close to ${719}$ as possible without going over ${719}$. $\begin{aligned} {57} +100}=157\\\\ {157} +100}= 257\\\\ {257} +100}= 357\\\\ {357} +100}= 457\\\\ {457} +100}= 557\\\\ {557} +100}= 657 \end{aligned}$ If we add $6 \text{ hundreds}}$, or $6 00}$, we reach $657$. We cannot add any more hundreds without going over ${719}$. ${57}$ ${719}$ ${657}$ $+600$ Next, let's add tens to $657$ until we get as close to ${719}$ as possible without going over ${719}$. $\begin{aligned} 657 +{10}=667\\\\ {667} +{10}= 677\\\\ {677} +{10}= 687\\\\ {687} +{10}= 697\\\\ {697} +{10}= 707\\\\ {707} +{10}= 717 \end{aligned}$ If we add ${6 \text{ tens}}$, or ${60}$, we reach $717$. We cannot add any more tens without going over ${719}$. ${57}$ ${719}$ ${657}$ ${717}$ $+600$ $+60$ Finally, how many ones should we add to $717$ to get to ${719}?$ $717 +{2}={719}$ ${57}$ ${719}$ ${657}$ ${717}$ $+600$ $+60$ $+2$ We added $6 \text{ hundreds}}$, ${6 \text{ tens}}$, and ${2\text{ ones}}$ to ${57}$ to get to ${719}$. $6 00}+{6 0}+{2}={662}$ ${57}$ ${719}$ ${657}$ ${717}$ $+600$ $+60$ $+2$ $+662$ $719 = 57 +{662}$